This project uses the comparative method as a technique to better understand the functions of play in the behavioral repertoire of developing squirrel monkeys. Statistical analysis and manuscript preparation relating to data collected in the prior year was completed. In this study of social play in 10 yearling squirrel monkeys of the Roman-arch variety two types of play wrestling were identified which differed in the degree of roughness, and were used with different frequencies by males and females. Partner choice and type of play were shown to be strategies used by animals to maximize their chances of winning in play interactions. By using some behaviors selectively to initiate play, animals were able to manipulate the type of wrestling that occurred. Both sexes initiated play more often with same-sex partners, and males responded more often than did females to initiation attempts by either sex. While dominance relationships outside of play remained stable, role reversal characterized both male-male and female-female play, but not male-female play. Males dominated females both during and outside of play. Role reversal represents a strategy encouraging play between youngsters of diverse abilities and provides needed experience in a variety of social roles.